Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental condition in children and adolescents and is often associated with difficulties in attention, inhibitory control, working memory, and other executive functions. The fronto-parietal brain network is thought to play an important role in these cognitive functions. Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation technique that may influence brain activity. This study aims to evaluate whether 5-Hz tACS targeting the right frontal and parietal regions can improve executive functioning in children and adolescents aged 6 to 18 years with ADHD. The study also aims to explore whether any effects of tACS are related to changes in brain activity measured by electroencephalography (EEG). Participants will receive both active tACS and sham stimulation in a randomized, double-blind, crossover design. Clinical symptoms, executive function performance, and EEG measures will be assessed before and after each stimulation session. The main hypothesis is that active fronto-parietal tACS will produce greater improvement in executive functioning than sham stimulation, and that these effects may be associated with changes in EEG-measured brain activity.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
TRIPLE
Enrollment
38
Active transcranial alternating current stimulation (tACS) will be delivered over the right frontoparietal region using a multi-electrode montage. Electrodes will be placed at F4, F2, AF4, and F6 over the right frontal region, and at P4, CP4, P6, and PO4 over the right parietal region. F4 and P4 will be configured as return electrodes according to the stimulation protocol. The stimulation will be applied as a 5-Hz sinusoidal alternating current with a total current intensity of 2 mA. Each stimulation session will last 12 minutes, including 60-second ramp-up and 60-second ramp-down periods.
Sham transcranial alternating current stimulation will use the same electrode montage, device appearance, and setup procedures as active tACS. Electrodes will be placed at F4, F2, AF4, and F6 over the right frontal region, and at P4, CP4, P6, and PO4 over the right parietal region. F4 and P4 will be configured as return electrodes as in the active stimulation condition. The sham procedure will include brief ramp-up and ramp-down periods of approximately 60 seconds to mimic the sensory experience of active stimulation, with no sustained current delivered.
Department of Psychiatry, The Second Xiangya Hospital of Central South University
Changsha, Hunan, China
Change in attention performance measured by the Test of Attentional Performance for Children
Attention performance will be assessed using the Test of Attentional Performance for Children, including seven child-adapted attention subtests covering alertness, distractibility, divided attention, cognitive flexibility, response inhibition, sustained attention, and visual scanning. Outcome indices include reaction time, reaction time variability, accuracy, omission errors, commission errors, and other task-specific performance measures. In general, shorter reaction time, lower reaction time variability, higher accuracy, and fewer errors indicate better attention performance.
Time frame: Before the first stimulation session, immediately after the first stimulation session, before the second stimulation session after a washout interval of at least 2 days, and immediately after the second stimulation session.
Change in task-related EEG indices during the visual search task
Task-related electroencephalography will be recorded during a visual search task in which participants identify the direction of a visual target and respond using a joystick. EEG outcomes will include event-related potential measures, such as N2pc amplitude and latency, time-frequency measures across predefined frequency bands, and alpha-band channel tuning function indices reflecting spatially selective neural responses. These measures do not have a fixed clinical score range.
Time frame: Before the first stimulation session, immediately after the first stimulation session, before the second stimulation session after a washout interval of at least 2 days, and immediately after the second stimulation session.
Change in ADHD symptoms measured by the SNAP-IV Parent Rating Scale
ADHD symptoms will be assessed using the parent-rated Swanson, Nolan, and Pelham-IV Rating Scale 26-item version (SNAP-IV). The scale includes items assessing inattention, hyperactivity/impulsivity, and oppositional symptoms. Each item is rated on a 4-point scale: 0 = not at all, 1 = just a little, 2 = quite a bit, and 3 = very much. Total score and subscale scores are calculated by summing or averaging the relevant items. Higher scores indicate more severe ADHD-related and oppositional symptoms.
Time frame: Before the first stimulation session, immediately after the first stimulation session, before the second stimulation session after a washout interval of at least 2 days, and immediately after the second stimulation session.
Change in abnormal behaviors measured by the Aberrant Behavior Checklist-Second Edition
Behavioral abnormalities will be assessed using the Aberrant Behavior Checklist-Second Edition (ABC-II). The ABC-II evaluates the frequency and severity of behavioral problems. Each item is rated on a 4-point scale: 0 = not a problem, 1 = the behavior is a problem but slight in degree, 2 = the problem is moderately serious, and 3 = the problem is severe. The total score is calculated by summing all item scores. Higher scores indicate more severe and widespread behavioral problems.
Time frame: Before the first stimulation session, immediately after the first stimulation session, before the second stimulation session after a washout interval of at least 2 days, and immediately after the second stimulation session.
Change in depressive symptoms measured by the Patient Health Questionnaire-9
Depressive symptoms will be assessed using the Patient Health Questionnaire-9 (PHQ-9). The PHQ-9 includes 9 items assessing depressive symptoms during the past two weeks. Each item is rated on a 4-point scale: 0 = not at all, 1 = several days, 2 = more than half the days, and 3 = nearly every day. The total score ranges from 0 to 27, with higher scores indicating more severe depressive symptoms.
Time frame: Before the first stimulation session, immediately after the first stimulation session, before the second stimulation session after a washout interval of at least 2 days, and immediately after the second stimulation session.
Change in anxiety symptoms measured by the Generalized Anxiety Disorder-7 scale
Anxiety symptoms will be assessed using the Generalized Anxiety Disorder-7 scale (GAD-7). The GAD-7 includes 7 items assessing the frequency of anxiety-related symptoms during the past two weeks. Each item is rated on a 4-point scale: 0 = not at all, 1 = several days, 2 = more than half the days, and 3 = nearly every day. The total score ranges from 0 to 21, with higher scores indicating more severe anxiety symptoms.
Time frame: Before the first stimulation session, immediately after the first stimulation session, before the second stimulation session after a washout interval of at least 2 days, and immediately after the second stimulation session.
Change in sleep problems measured by the Sleep Disturbance Scale for Children
Sleep problems will be assessed using the Sleep Disturbance Scale for Children (SDSC). The SDSC is a parent-rated questionnaire assessing sleep-related problems in children and adolescents. Items are rated according to the frequency or severity of sleep disturbances on a 5-point scale. The total score is calculated by summing item scores. Higher scores indicate more severe sleep disturbances.
Time frame: Before the first stimulation session, immediately after the first stimulation session, before the second stimulation session after a washout interval of at least 2 days, and immediately after the second stimulation session.
Change in sensory processing symptoms measured by the Short Sensory Profile
Sensory processing symptoms will be assessed using the Short Sensory Profile (SSP). The SSP is a parent-rated questionnaire assessing sensory processing patterns and sensory-related behavioral responses in children. Each item is rated on a 5-point scale according to how frequently the child shows a specific sensory response. The total score is calculated by summing item scores. Lower scores generally indicate greater sensory processing difficulties, whereas higher scores indicate fewer sensory processing difficulties.
Time frame: Before the first stimulation session, immediately after the first stimulation session, before the second stimulation session after a washout interval of at least 2 days, and immediately after the second stimulation session.
Change in selective attention performance during the joystick-based visual search task
Selective attention performance will be assessed using a joystick-based visual search task. Participants will be asked to identify the direction or location of a visual target and respond using a joystick. Behavioral outcome indices will include predefined task performance measures, such as reaction time, movement time, response accuracy, response variability, omission errors, commission errors, and other task-specific joystick response measures. In general, shorter reaction time and movement time, lower response variability, higher accuracy, and fewer errors indicate better selective attention performance.
Time frame: Before the first stimulation session, immediately after the first stimulation session, before the second stimulation session after a washout interval of at least 2 days, and immediately after the second stimulation session.
Change in resting-state EEG spectral parameters
Resting-state electroencephalography will be recorded to assess spontaneous neural activity. EEG spectral outcomes will include power measures across predefined frequency bands and parameterized spectral measures derived from the power spectrum, such as aperiodic offset, aperiodic exponent, and periodic oscillatory components. These measures do not have a fixed clinical score range.
Time frame: Before the first stimulation session, immediately after the first stimulation session, before the second stimulation session after a washout interval of at least 2 days, and immediately after the second stimulation session.
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